Broad Branch is a tributary of Rock Creek in Washington DC, and Linnean Creek is a tributary of Broad Branch.  The Broad Branch stream restoration project was needed because a portion of the stream was put in a pipe and because uncontrolled stormwater had caused erosion that created unstable gullies and led to sedimentation in the mainstem of Broad Branch. This destabilized the surrounding environment, reduced infiltration of water into underlying aquifers, and compromised wildlife habitat. When this portion of Broad Branch was piped the stormwater flowing to it was untreated and without intervention the hot, fast stormwater flows would have continued to degrade and pollute the stream. 

The restoration project took a portion of Broad Branch that was piped underground in 1937 and restored it to its historic channel, a process known as “daylighting.” This will help process and remove pollutants from the stream by exposing it to sunlight, air, soil, and vegetation.  It will also reduce nutrient and sediment pollution from erosion caused by fast-flowing stormwater and non-point source pollution by increasing groundwater infiltration and creating meanders and floodplain wetlands.  As a part of the project additional surface flow from adjacent streets and rooftops was directed to the area by creating curb cuts and redirecting storm sewers to rain gardens further slowing, cooling, and filtering stormwater in the subwatershed.

The method chosen for this restoration work is called regenerative stream channel (RSC), also known as a coastal plain outfall.  It is a specialized stream restoration technique that utilizes sand, wood chips, stone and logs to create a system of physical features, chemical processes, and biological mechanisms that greatly reduce erosive forces and positively impact the ecology of a drainage area. 

There are four governmental agencies involved in this project, the Department of the Environment (DDOE), the Department of Transportation (DDOT), the District of Columbia Water and Sewer Authority (DC WASA), and the National Park Service (NPS).  The restored Broad Branch will be a beautiful addition to the National Park Service’s Rock Creek Park in Northwest. 

If you used the other activities in the Benthic Macroinvertebrate Portal prior to using this activity, you should have a good understanding of everything you did in A Virtual Stream Sampler.  If you haven't used those activities, we suggest you run through the Introduction to Stream Sampling to get the basics. 

Click here to see a summary of the BMIs you picked in the Broad Branch/Linnean Creek Virtual Stream.

This section of Broad Branch begins as a small spring (left) that has been piped underground from this point on since 1937.  Soon, the water from this spring will again flow above ground through this culvert (right).
Restoration using the regenerative stormwater conveyance (RSC) technique creates a series of step pools that utilize a variety of massive and small woody debris to absorb the power of stormwater runoff and provide surfaces for biological activity.
Keith Underwood (left), the designer of this restoration, gives a tour of the Linnean Creek part of this restoration to Department of the Environment staff.  At right you see the culvert where Linnean Creek is temporarily forced underground to get under the road.
It took a number of weeks for the Linnean Creek restoration to fill with water, because this restoration approach fills more than the surface channel with water.  It restores an active floodplain and water has to fill the underground portion of this watershed first.  Hydrating the floodplain in this way helps keep the stream flowing during dry periods.

Your Score

The benthic macroinvertebrate section is worth 50% of the total score, the other two sections are each worth 25% of final score. 

• In the benthic macroinvertebrate section, if there are 15 organisms, then finding everything in the net is worth 15 points, and correctly identifying everything is worth 15 points, for a total of 30 points (100%).  You are penalized heavily if you guess at answers on the list and get them wrong.  Every wrong guess is a point off.  Since you have three chances to guess at the answer for each organism before you are forced to use the dichotomous key, with 15 organisms that would be 45 points off.  Yes, you can get a very negative score.  So, if you don't know what something is, don't guess - use the key.  Guessing in the key is not penalized.

• The habitat section has a maximum score of 5.  Each wrong answer counts off one.  Each question you don't try to answer counts off two.  So you are better off guessing and being wrong than not answering at all.  If you don't guess on anything you can get a negative 100% score in this section.  Ouch!

• The water quality section has a maximum score of 6.  Each wrong answer counts one off.  Each question you don't try to answer counts 2 off.  So you are better off guessing and being wrong than not answering at all.   If you don't guess on anything you can get a negative 100% score in this section.  Ouch!

• Even though you can get negative scores in each section, the worst total score you can get is zero. 

The Stream Score

Aquatic organisms can be used as indicators of water quality. The advantage of using aquatic organisms over chemical indicators - such as the amount of a certain chemical in a water sample - is that animals are constantly "sampling" their environment.  The communities of organisms found in benthic samples are indicative of water quality conditions over time. Chemical measures, in contrast, provide a momentary snapshot of conditions in a constantly changing environment. 

Many years ago, the focus was on "indicator species."  An indicator species is one that, by its presence, absence, or abundance relative to other organisms, indicates environmental conditions. For example, the presence of numerous  non-biting midge (Chironomidae) larvae in a stream may indicate severe organic pollution.

Over the years, researchers generally moved away from the use of individual indicator species and toward "metrics" that look at groups of species. A typical metric might look at the total number of different species or the relative abundance of different species. For instance, if a researcher finds that species tolerant of degraded water quality outnumber kinds that are intolerant of pollution, it is more likely that degraded conditions exist  But the mere presence of pollution-tolerant organisms does not necessarily equate to water quality problems, because these organisms are often widely distributed.

A Virtual Stream Sampler scores the stream using two popular methods in use by volunteers in the Chesapeake Bay Watershed, the West Virginia Save Our Streams Stream Score Index, and Virginia Save Our Streams Stream Score.  Both of these scores are based on a suite (a group) of "metrics" that, when averaged together, are an effective way to tell a stream's story.  Two metrics are used by both West Virginia and Virginia:

• percent tolerant organisms tells you what percentage of the organism in the sample are tolerant of pollution, and

• Virginia's percent Mayflies, Stoneflies, and most Caddisflies is similar to West Virginia's % EPT score.  This score looks at what percentage of the sample consist of theswe three groups of insects that are mostly sensitive to pollution.  Virginia's score breaks out the pollution tolerant "common netspinner caddisfly."

The two tables below provide details on each system, and links for more information. 

Virginia SOS Stream Score
Metric	Your Metric Score	Good (2)	OK (1)	Poor (0)
% Mayflies, Stoneflies, and Most Caddisflies	X%	> 32.2	16.1 to 32.2	< 16.1
% Common Netspinner	X%	< 19.7	19.7 to 34.5	> 34.5
% Lunged Snail	X%	< 0.3	0.3 to 1.5	> 1.5
% Beetle	X%	> 6.4	3.2 to 6.4	< 3.2
% Tolerant Organisms	X%	< 46.7	46.7 to 61.5	> 61.5
% Non-Insect Organisms	X%	< 5.4	5.4 to 20.8	> 20.8
Get details on how the Virginia Save Our Streams Score is calculated and learn much more about the Virginia program.		Total # of 2s:	Total # of 1s:	Total # of 0s:
		N2	N1	N0
		Multiply by 2:	Multiply by 1:	Multiply by 0:
		N2 x 2 = S2	N1 x 1 =S1	N0 x 0 = S0
Now add the 3 subtotals (S2 + S1 +  S0) to get the Save Our Streams Multimetric Index Score
_____ Acceptable Conditions (9 to 12)               _____ Conditions cannot be Determined - Gray Area (8)                _____ Unacceptable Conditions (0 to 7)